Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 493 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a battery cell
2. 2.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) yeast (d) a magnet
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
5. 5.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) a cotton bud
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
10. 10.True or false: ironing the paper is a job for an adult. (a) True (b) False
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a cotton bud (d) a small bowl
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a balloon (d) a cotton bud
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
15. 15.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) cutting the lemon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the ironing time
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) turmeric powder
21. 21.True or false: yeast is needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a small bowl (d) yeast
23. 23.True or false: writing the message is a job for an adult. (a) True (b) False
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
26. 26.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
28. 28.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a small bowl (d) a cotton bud
30. 30.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a small bowl (d) a cotton bud
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
37. 37.True or false: reading the message is a job a child can do. (a) True (b) False
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) writing the message
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a balloon (d) a cotton bud

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